When Push Comes to Shove:
The Tectonics of Mountain Building

Wherever tectonic plates collide, thick piles of
crustal rocks that are caught between the converging plates are squeezed and
thrust into enormous deformed zones called thin-skinned fold-and-thrust
belts. As much as 10 to 20 kilometers thick, and up to hundreds of
kilometers across, these mountain belts are the sites of major earthquakes,
and in their submarine variety, where they are called accretionary wedges,
they produce the largest of all earthquakes (including the one that cause
the great Indian Ocean tsunami). They are responsible for forming
sedimentary basins that contain many of the greatest oil deposits. From
their active youth (like the present-day Himalayas) to their eroded,
inactive, yet still majestic old age (like the present-day Appalachians),
they form impressive natural barriers capable of affecting everything from
human culture to the weather.

Professor Davis will show some of the results of fieldwork and
laboratory experiments that have shed light into how the world’s great (and
not-so-great) mountain belts form.

Dan Davis is a Professor of Geophysics whose main
research interests involve the mechanics of large-scale crustal deformation.
He is particularly interested in the mechanics of thin-skinned mountain
belts and the role of pore fluids and basement structure in the development
of accretionary wedges at convergent plate margins. Professor Davis is well
known for applying a model for the development of mountain belts that is
similar to a bulldozer pushing sand.

A Thousand and One Nights on
the Surface of Mars

On the evening of this presentation, the Mars
Exploration Rover Spirit will have just surpassed one thousand
Martian days (sols) of operation in Gusev crater. The rover Opportunity,
approaching Sol 1000, continues to explore Meridiani Planum on the opposite
side of the planet. The rovers have survived more than ten times their
primary missions of 90 sols each. Although they are beginning to show signs
of old age, both rovers still retain mobility, are able to make use of their
entire scientific instrument suites, and continue to return an unprecedented
amount of data from the Martian surface.

Power-starved Spirit has spent the past 200 sols
in a stationary "winter haven" position on Low Ridge in the Columbia
Hills. From this location it has obtained a remarkably detailed set of
scientific observations of its immediate surroundings. For two years since
leaving Endurance crater, Opportunity has been driving steadily
southward, on its way to the 800 m diameter Victoria crater. Along the
traverse it has stopped at several small craters and outcrops to continue
its investigations of evidence for flowing water on the ancient surface of
Mars.

In this presentation, Professor McLennan will review
the recent scientific accomplishments of the Mars Exploration Rovers and
discuss the plans for exploration during the coming martian summer.

In-service credit available for teachers

If your school requires that you have a
sequence of educational opportunities in order to receive in-service credit,
please advise them that during the Fall Semester we will be offering one-hour
of in-service credit for each of the: